Carrier Ethernet networks are continuing to evolve to provide high speed Ethernet technology for metro area networks. This evolution is driving the replacement of network equipment from switched transport equipment, such as Ethernet Provider Bridge technology, to Connection Oriented Packet Switched (CO-PS) technology. Such replacement of network equipment is aimed at improving the reliability for transmitting communications traffic through the network. In this regard Transport Multi Protocol Label Switching (T-MPLS) and Multi Protocol Label Switching Transport Profile (MPLS-TP) have been previously considered for such Carrier Ethernet networks.
There are many types of protection mechanisms that may be used in a CO-PS network. Such protection mechanisms aim to provide protection to the network in the event of failure of a path, link, or device within the network so that disruptions to communications services are reduced. It is known to use 1+1 protection where traffic in the network is actively transmitted from a source node to a sink node on both a worker path and a main protection path. It is also known to use 1:1 protection where the traffic is only transmitted on the working path but a main protection path is allocated and used for sending traffic when a failure of the worker path occurs. Such 1+1 or 1:1 protection may be implemented as Revertive protection or Non-Revertive protection. Revertive protection requires that traffic is switched to a protection path when the worker path fails, and then back to a worker path when the worker is available for use. Non-Revertive protection requires that traffic stays on the protection path even when the worker path is available for use.
It is further known to provide static and dynamic protection schemes for a communications network. The 1+1 and 1:1 protection mechanisms described above are examples of static protection whereby the required protection is planned in advance of a failure occurring. Dynamic protection may be defined as the determining of the required protection after a failure occurs.
A management plane is typically used in a communications network to carry any operation and administration traffic that may be required for network management. This traffic may include configuration traffic or maintenance traffic for configuration and maintenance purposes. A control plane is also typically used in the communications network to perform routing of user traffic to define where packets are to be sent within the network. Standardisation activities for MPLS-TP are continuing to develop, and the current standards define a control plane as an optional feature. Standardisation activities for T-MPLS are more advanced, but the current standards do not define a control plane. Typically, when a control plane is not present in a communications network, the management plane is used to provide configuration and monitoring of the network only for static protection schemes. In the absence of a control plane the use of dynamic protection schemes is not considered.
Using only static protection schemes for handling failures in a network can lead to a number of problems. In the event of a multiple failure within the network, the network operator must follow specific procedures to manually restore the communications traffic. Such manual restoration procedures are generally very time consuming and may incur a high operational expenditure for the network. In addition, the need for manual intervention in the case of multiple faults may lead to a higher network down-time which can have a negative impact on Quality of Service and Service Level Agreements. Furthermore, static protection schemes require network resources to be pre-allocated which represents sub-optimal use of bandwidth availability within the network. Overall, the use of only static protection schemes may not utilise network resources efficiently.